1. Field of the Invention
The present invention relates to a living tissue ligation device which is endoscopically inserted into a body cavity and ligates living tissue with a clip.
2. Description of the Related Art
As a living tissue ligation device, for example, Jpn. Pat. Appln. KOKAI Publication No. 8-280701 has been known. As a polypectomy snare device, WO 01/10321A1 has been known. Jpn. Pat. Appln. KOKAI Publication No. 8-280701 discloses a device which is designed such that when a clip having a pair of arms which grip living tissue is fitted in a clamping ring, the arms of the clip are closed, and when the clip is made to protrude from the clamping ring, the arms spread apart. The clip and clamping ring can be housed in an introduction tube which is made to extend through a channel of an endoscope. The clip is connected, through a coupling member, to an operating wire which is made to retractably extend through the introduction tube.
According to this device, the clip can be closed and opened by moving the operating wire back and forth using an operator-side operating portion. In addition, the orientation of the clip can be changed by rotating the operating wire using a rotating operating member of the operator-side operating portion. This makes it possible to approach the clip to a target region.
According to the device disclosed in WO 01/10321A1, a snare is provided at a distal end portion of a shaft retractably extending through a sheath. This device comprises a first handle which changes the orientation of the snare by rotating the snare and a second handle which opens/closes the snare.
A patent application for a clip case which houses a clip unit has already been filed as Japanese Patent Application No. 2001-244402. This clip case is molded by a transparent synthetic resin material, and the clip unit is sterilized while being housed in the clip case. The clip case is designed to be connected to the operating wire extending through the introduction tube without being touched with fingers while being housed in the clip case.
For this purpose, the clip case has a clip unit housing portion and introduction tube insertion portion. When the introduction tube is inserted into the clip case through the introduction tube insertion portion, the introduction tube is pressed with elastic restoring force by the elastic press portion provided for the clip case. When the operating wire extending through the introduction tube is moved forward, the arrowhead hook provided at the distal end portion of the operating wire elastically engages with the coupling member of the clip unit.
The devices disclosed in Jpn. Pat. Appln. KOKAI Publication No. 8-280701 and WO 01/10321A1 are structured to change the orientations of the clip and snare by rotating them using the operator-side operating portion. However, this structure is designed to rotate the operating wire, and hence a large torque cannot be obtained, and the structure becomes complicated.
According to the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 8-280701, even while living tissue is ligated by pulling the clip into the clamping ring and closing the arms of the clip, the clamping ring is only pressing the clip so as to close the arms. Therefore, the gripping force applied to the living tissue may decrease.
The clip case disclosed in Japanese Patent Application No. 2001-244402 is structured to press the introduction tube with the elastic restoring force of the elastic press portion provided for the clip case. This force is insufficient as holding force for the introduction tube. Therefore, the introduction tube is moved to a direction to come off the introduction tube insertion portion of the clip case owing to the reactive force generated when the operating wire is moved forward to elastically engage the arrowhead hook with the coupling member. This makes it impossible to engage the arrowhead hook with the coupling member by one-touch operation.
If the elastic restoring force of the elastic press portion is increased to solve this problem, the insertion force required for the introduction tube also increases. By repeatedly mounting the clip on the introduction tube, an excessive load is placed on the introduction tube. This may induce buckling of the introduction tube.